Eoseristalis
Guides
Eristalis brousii
Hourglass Drone Fly
Eristalis brousii, commonly known as the hourglass drone fly, is a hoverfly species first described by Samuel Wendell Williston in 1882. The species has experienced severe population decline across North America following the introduction of the European congener Eristalis arbustorum near Toronto around 1885. As of 2019, it persists only along the lake margin of Hudson Bay in Northern Canada, making it one of the most geographically restricted hoverflies on the continent. Like other Eristalis species, adults are pollinators while larvae develop as aquatic filter-feeders.